Columnea latent viroid - The Food and Environment Research ...

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Fera Pest Risk Analysis for Columnea latent viroid Authors: Claire Sansford, Jane Morris Version: 3; revision of version 2 (change of personal communication contact from Thailand) Date: 21 st January 2010; version 2 - 13 th October 2009; version 1 - 15 th May 2009 PPP file: 12362 Costa Rica were tested, but no viroids could be detected (Hammond et al., 1989). There are indications from other sources that CLVd may be present in other countries but there are no published records for any of these, details are given below: The UK outbreaks in tomato plants in 2007 were all in crops that had been grown from seed originating in Taiwan, arriving in the UK via France. However, seed transmission for CLVd has not been proven (Hadidi et al., 2003). There are no published records of CLVd in Taiwan. However, subsequent to the first version of this PRA a record has been published of CLVd in tomato crops in western France occurring in the summer of 2007. The origin of infection of these crops is unknown (Steyer et al., 2009). In the summer of 2009, a UK fruit crop of tomato cultivars (cv.’s) Angelle and Santazian was found to be infected with CLVd; this crop is subject to eradication. There are no further details of this outbreak available at present. (P. Reed, Fera, UK, personal communication, 2009). Nucleotide sequence accessions are present on the National Centre for Biotechnology Information (NCBI) database (NCBI, undated) for CLVd (strains not assigned) from tomato plants in Portugal, accession number EF015581. However, there are no published records of CLVd in Portugal. NCBI accessions are also recorded for two tomato isolates numbered AM698093 and AM698094. These derive from tomato seeds imported into Thailand which were tested in post-entry quarantine and destroyed once infection with CLVd was detected (P. Tangkanchanapas, Plant Quarantine Research Group, Department of Agriculture, Bangkok, Thailand, personal communication, 2009). The origin of the seed is unknown. 7. Is the pest established or transient 3 in the PRA area? (Include information on interceptions and outbreaks here). The pest is considered to be transient in the PRA area in tomato crops. In 2007 there were four confirmed outbreaks of the viroid in the UK in glasshouse tomato crops (cv. Santa). These were the first findings of CLVd in the UK. (EPPO, 2008; Nixon et al., 2009). These outbreaks were eradicated. There were no findings in the UK in 2008. However, in 2009 a single outbreak occurred in a tomato crop (cv.’s Angelle and Santazian). This is subject to eradication. The status in ornamental hosts in the UK is unknown as the natural hosts (that are known about) are asymptomatic and no surveys have been undertaken to date to determine the status of CLVd on plants grown in UK ornamental nurseries. Further information on potential pathways of entry including the possible entry via seed is given in sections 12 and 13. 3 Transience: presence of a pest that is not expected to lead to establishment (ISPM No., FAO, Rome) 4
Fera Pest Risk Analysis for Columnea latent viroid Authors: Claire Sansford, Jane Morris Version: 3; revision of version 2 (change of personal communication contact from Thailand) Date: 21 st January 2010; version 2 - 13 th October 2009; version 1 - 15 th May 2009 PPP file: 12362 8. Is there any reason to suspect that the pest is already established in the PRA area? Not in tomato crops. The first findings of CLVd in tomato in the UK were in 2007 and symptoms were detected early (April) in the cropping season. There were no findings in tomato in 2008, but in July 2009 a fruiting crop was found infected with CLVd; this is subject to eradication. There are no further details of this outbreak at present. UK tomato fruit crops are surveyed annually by the Plant Health Service (PHS) for Pepino mosaic virus and Potato spindle tuber viroid and more frequently for those grown for propagation. Although CLVd is symptomatic in tomato, the 2007 and 2009 outbreaks were detected/reported several months apart. For this reason, it is not possible to state that the official inspections carried-out by the UK PHS would detect the presence of the viroid based upon symptoms alone. However, affected growers are likely to notice the symptoms and if sampled, testing would detect whether or not CLVd was present. It is not known whether CLVd is established in ornamental hosts in the UK. There are four reported natural hosts but only one of them, tomato, is symptomatic. The three remaining hosts are all ornamental species and are asymptomatic. 9. What are the pest’s host plants? List natural and experimental hosts. Natural hosts are listed in Table 2 and the results of experimental transmission studies to other plant species are shown in Table 3; described below. The viroid was first detected because seedlings of tomato (L. esculentum) inoculated with low molecular weight RNA preparations obtained from asymptomatic C. erythropae (lipstick vine) from a US nursery, developed symptoms (Owens et al., 1978). The viroid was further characterised by Hammond et al. (1989) who found it was transmissible to Gynura aurantiaca (purple velvet plant), Cucumis sativus (cucumber) as well as tomato (L. esculentum), but not to Nicotiana tabacum (tobacco plant). Unpublished results (Diener, Smith and Owens; cited by Hammond et al., 1989) showed transmission of the CLVd isolate from C. erythrophae, to potato (S. tuberosum). CLVd-N, isolated from symptomatic N. wettsteinii (Goldfish plant) plants in Canada (Singh et al., 1992) (now CLVd-nem; ICTV, 2005) was experimentally transmissible to tomato, potato and the ornamental plant Scopolia sinensis. CLVd-B, isolated from symptomless B. undulata (Jamaican raintree) in Germany (Spieker, 1996) (now CLVd-bru; ICTV, 2005) was found to be transmissible to tomato. 5
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